Pneumococcal population dynamics: Investigating vaccine-induced changes through multiscale modelling

Area of Science:

• Microbiology
• Epidemiology
• Mathematical Modeling

Background:

• Vaccine-induced strain replacement in Streptococcus pneumoniae (pneumococcus) is not fully understood.
• Distinct pneumococcal lineages can co-colonize hosts and generate novel recombinants during natural infections.
• Observed post-vaccination replacement patterns suggest competition between specific pneumococcal lineages.

Purpose of the Study:

• To investigate how within-host dynamics influence ecological patterns of pneumococcal colonization before and after vaccination.
• To model the competition between and within pneumococcal strains based on their antigenic, metabolic, and resistance profiles.

Main Methods:

• Development of a multiscale transmission model.
• Inclusion of co-colonization and recombination dynamics within hosts.
• Analysis of strain fitness based on antigenic, metabolic, and resistance characteristics.

Main Results:

• Model results indicate that antigenic and resistance profiles are critical drivers of pneumococcal strain success post-vaccination.
• Within-host dynamics, including co-colonization and recombination, significantly shape observed ecological patterns.
• Competition between specific pneumococcal lineages is a key factor in vaccine-induced replacement.

Conclusions:

• Antigenic and resistance properties of pneumococcal strains are crucial determinants of their ecological success in the face of vaccination.
• Understanding within-host dynamics is essential for predicting and managing vaccine-induced strain replacement.
• The study provides a framework for investigating the complex interplay between host, pathogen, and vaccination in shaping microbial populations.